United States Steel Corp. posted sharply higher second-quarter profit Tuesday, surpassing Wall Street expectations, as surging demand and prices boosted results to record levels. US Steel's net income more than doubled to $668 million, or $5.65 per share, for the three months ended June 30, compared with $302 million, or $2.54 per share, during the same period last year. Revenue climbed 60 percent to $6.74 billion from $4.23 billion in the second quarter of 2007, the company said. The results easily beat Wall Street estimates. Analysts, on average, predicted earnings of $3.91 per share, according to a survey by Thomson Financial. Substantial price increases across US Steel's three business segments - flat-rolled, European operations and tubular - outpaced increases in raw materials, the company said. “We recorded the highest quarterly sales and net income in US Steel's history during the second quarter as all three reportable segments posted record results,” John Surma, US Steel's chairman and chief executive, said in a statement. The results reflect strong operating performance and favorable global pricing dynamics, he said. Looking ahead to the July-September period, Surma said the company expects “another excellent quarter,” with growth driven by higher prices set in the second quarter and early third quarter. The second quarter results included an inventory charge related to US Steel's acquisition of Canadian steel maker Stelco Inc., now called US Steel Canada. That reduced net income by $4 million, or 3 cents per share.